diff --git a/jedi/evaluate/iterable.py b/jedi/evaluate/iterable.py
index eee58868..3ee4f529 100644
--- a/jedi/evaluate/iterable.py
+++ b/jedi/evaluate/iterable.py
@@ -819,7 +819,6 @@ def create_index_types(evaluator, index):
     Handles slices in subscript nodes.
     """
     if tree.is_node(index, 'subscript'):  # subscript is a slice operation.
-        start, stop, step = None, None, None
         result = []
         for el in index.children:
             if el == ':':
diff --git a/jedi/parser/tree.py b/jedi/parser/tree.py
index 10fbeccd..04677601 100644
--- a/jedi/parser/tree.py
+++ b/jedi/parser/tree.py
@@ -377,6 +377,10 @@ class Name(Leaf):
                                    self.start_pos[0], self.start_pos[1])
 
     def is_definition(self):
+        if self.parent.type in ('power', 'atom_expr'):
+            # In `self.x = 3` self is not a definition, but x is.
+            return False
+
         stmt = self.get_definition()
         if stmt.type in ('funcdef', 'classdef', 'file_input', 'param'):
             return self == stmt.name
diff --git a/test/completion/arrays.py b/test/completion/arrays.py
index e2ec70d8..c2aba71e 100644
--- a/test/completion/arrays.py
+++ b/test/completion/arrays.py
@@ -386,3 +386,18 @@ recursion1([1,2])[0]
 for x in [1] + ['']:
     #? int() str()
     x
+
+# -----------------
+# For loops with attribute assignment.
+# -----------------
+def test_func():
+    x = 'asdf'
+    for x.something in [6,7,8]:
+        pass
+    #? str()
+    x
+
+    for x.something, b in [[6, 6.0]]:
+        pass
+    #? str()
+    x